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Abstract：
Current practices for structural analysis of extremely large-molecular-weight polysaccharides via solution-state nuclear magnetic resonance (NMR) spectroscopy incorporate partial depolymerization protocols that enable polysaccharide solubilization in suitable solvents. Non-specific depolymerization techniques utilized for glycosidic bond cleavage, such as chemical degradation or ultrasonication, potentially generate structural fragments that can complicate complete and accurate characterization of polysaccharide structures. Utilization of appropriate enzymes for polysaccharide degradation, on the other hand, requires prior structural knowledge and optimal enzyme activity conditions that are not available to an analyst working with novel or unknown compounds. Herein, we describe an application of a permethylation strategy that allows the complete dissolution of intact polysaccharides for NMR structural characterization. This approach is utilized for NMR analysis of Xylella fastidiosa extracellular polysaccharide (EPS), which is essential for the virulence of the plant pathogen that affects multiple commercial crops and is responsible for multibillion dollar losses each year.
摘要：
通过溶液状态核磁共振（NMR）光谱法对分子量极大的多糖进行结构分析的当前实践引入了部分解聚方案，该方案使多糖能够在合适的溶剂中溶解。用于糖苷键裂解的非特异性解聚技术，如化学降解或超声处理，可能会产生结构片段，这些片段会使多糖结构的完整和准确表征复杂化。利用适当的酶降解多糖，另一方面,需要事先的结构知识和最佳的酶活性条件，这是分析师无法使用的新的或未知的化合物。在这里，我们描述了全甲基化策略的应用，该策略允许完整多糖完全溶解以进行NMR结构表征。此方法用于木耳尖顶胞外多糖（EPS）的NMR分析，这对于影响多种商业作物的植物病原体的毒力至关重要，每年造成数十亿美元的损失。
